I think the others in the rags are under the influence and orders of the others like ethan and the ones on the boat.
I also find it funny that when people talk about all these people on the island and all the people that have been to the island ( the others, our plane survivours, ressous' team, the nigeria drug smugglers etc) but noone ever mentions the fact that when Jack first goes to the caves, it is like a crypt with bodies and skeletons in there.